Pivot mounting



June 15,1925. 1,588,555

E. G. THOMAS PIVOT MOUNTING Filed Feb. 18, 1920 Patented June 15, 1926.

v UNITED STATES PATENT OFFICE.

EDVARD G. THOMAS, OF TOLEDO, OHIO, ASSEGNOR TO TOLEDO SCALE COMPANY, OF

TOLEDO, OHIO, A CORIEORATION OF NEW JERSEY.

rrvo'r MOUNTING.

Application filed February This invention relates to means for mountingknife edge pivots such as are used in instruments and machines in whichit is desirable to reduce friction to a minimum, and particularly tomeans for mounting such pivots in scale levers. As such levers are nowconstructed the knife edge pivots are usually placed in the mould inwhich the lever is to be cast and are thus fixed in place when the metalof the lever solidifies. In order that the scale may weigh properly, thepivots in the scale levers must be placed with great exactness, and thepractice of casting the levers with the pivots in place results in theloss of many castings owing to the pivots having been improperly placedor having shifted in the mould. Furthermore, the pivots lose theirtemper and often warp during the casting process and must be reshapedand re-hardened, which involves grinding and heat treating operationsthat, when the pivots are fixed in the lever, are difficult to carryout, especially if the lever be a heavy one. Vhere a pivot is thus fixedin place it must be formed of a bar of sufficient cross-section tosupport the weight, and as these bars are of high-grade steel, theircost is considerable. The practice of inserting the pivots in holesdrilled in the lever is also followed to some extent, but such insertedpivots must be formed of even heavier bars than are used to form pivotswhich are fixed in place in casting, and the cost of inserted pivotswhich are entirely formed of hardened steel is therefore also verygreat. o p

The principal object of this invention is to provide improved meanswhereby pivots containing a minimum amount of expensive metal may besecurely and accurately fixed to a scale lever.

Another object is to provide means for securely fixing a pivot to alever so that the pivot may be readily detached and replaced.

Still another object is to provide means for detachably securing a pivotto a lever so arranged that the parts may be accurately fitted with aminimum amount of machining.

Other objects and advantages will be apparent from the followingdescription, in

which reference had to the accompanying 18, 1920. Serial No. 359,581.

having pivots mounted thereon accor-ding' to my invention, parts beingbroken away; Figure 2 is an enlarged vertical section on the line 22 ofFigure 1;

Figure 3 is an end view of the pivot retainer and pivot of my invention;and

Figures 4 and 5 are similar views showing (modifications thereof.

Referring to the drawings in detail and particularly to Figures 1, 2 and3, the lever 1 on which pivots are to be mounted according to myinvention is provided with tapered openingsfor receiving the pivotretainers 2, the central portions of which are tapered, as at 3, to fitsnugly in the openings in the lever." Owing to this tapered formationthe pivot retainers may be driven into place so that they will be heldwith all necessary firmness, though they may, when necessary, be readilydriven out.

Substantially cylindrical projections 4.

are formed at the ends of each of the pivot retainers '2, and alignedlongitudinally-exten-ding grooves 5 having their sides sub stantially atright angles to each other are milled in the sides of the projectionsone side of each groove being of, considerable area to forma surfaceagainst which a pivot v6.may be clamped. The pivot retainers 2 may be ofrelatively inexpensive softsteel.

Each knife edge pivot 6 is formed of a bar of hardened steel with two ofits sides-parallel, one of these sides having a depression thereinadapted to receive the end of a curved clamping member 7 by means ofwhich it is finally clamped against the sides of the groove 5. In theillustrated embodi ments the pivot bar is substantially trapezijusted byplacing Shims 9 between the sides of the pivot bar and the groove in themanner shown in Figure 3. End thrust bearings at the inner ends of thepivot bars 6 are where it terminates in threaded boss 10 which receivesa set screw by means of which its opposite end may be drawninto firmengagement with the pivot bar 6 In the modification shown in Figure 5,registering bores extendv through the projection 4L and the pivot bar 6"so tnat the pivot bar may be clamped in ,place by means of an ordinarybolt 8'. In each of the modifications the pivot retainer is so turnedthat the knife edge of the pivot will lie directly above or below theaxis of the pivot retainer. 7

It will be apparent upon inspection. of the drawings that the clampsshown in Figures 3 and 4 act to force the bar against both sides of thegroove; that the pivots in any of the forms may be. readily removed bylo0ssuing the clamp; and that since it not wedged into place, there isno danger of rust causing it to stick so that it cannotbe easilydetached, r V

It is also apparent that since thegroove 5 is formed with straight sidesat right angles to each other and the knife edge of the pivot bar isformed at one of its corners, the parts may be. constructed and fittedtogether with less machining than would otherwise be necessary, and thatsince only the thickness and the width of one side need be considered induplicating the pivot bar, it can easily be replaced when it becomesworn.

lVhile it will be apparent that the illustrated embodiments of myinvention herein disclosed are well calculated to adequately fulfill theobjects primarily stated, it is to Having described my invention, Iclaim;

ing therethrough and secured thereto, said plvot, retainer having atwo-sided groove therein, a pivot b ar,and means for clamping said pivotbar in said groove. .7 V

v 3. In adevice of the class described, in combination, a lever, a pivotretainer passing therethrough and secured thereto, said pivot retainerhaving a two-sided groove therein, a pivot bar, and means for clampingsaid pivot bar against both sides of said groove.

t. In a device of the class described, in combination, a lever, a pivotretainer secured thereto, a pivot bar provided with a depression, and aclamping member engaging said pivot retainer and seating in saiddepression,

5; In a device of. the class described, in combination, a, lever, apivot retainer secured thereto, said pivot retainenbeing provided with atwo-sided groove, and a pivot bar of substantially trapeziformcross-section, two only or" the sides of said pivotbar being parallel,secured in said groove.

6. In a device of the class described, in combination, a lever, a pivotretainer s'ecured thereto, said pivot retainer having a two-sided groovetherein, and a pivot bar of substantially right trapeziform cross-section with two parallel sides and one acute edge having one of itsparallel sides clamped against the side of said groove and its acuteedge projecting from said retainer.

7. In a device ofthe class described, in combination, a lover, a pivotretainer secured thereto, said pivot retainer havinga twosided groovethereima pivot bar having two parallel sides, and a clamping memberpar-J tially encircling said retainer and engaging one of said parallelsides, the other parallel side lying against a side of said groove.

EDWARD e. THOMAS.

